Silicon ink targets RFIDs

PORTLAND, Ore.  Printing thin-film circuits on flexible substrates may be ready for prime time with the introduction Thursday (Oct. 16) of what is claimed as the first commercial application of silicon ink.

Kovio Inc. (Milpitas, Calif.) rolled out its silicon ink printing scheme at the Electronic Product Code conference in Chicago. The initial application will be RFID tags, with future applications ranging from printable sensors and flexible displays.

Kovio claims its process can reduce the cost of RFID tags using ink-jet printing by as much as 15 cents to between 5 to 10 cents each. High-volume roll-to-roll printing could further reduce costs to less than a penny.

"Kovio's printed integrated circuits will improve the value proposition and potentially speed adoption of tagging all objects, from retail products to transit passes to documents and other assets," predicted Leslie Hand, research director at Global Retail Insights (Framingham, Mass.)

Rival organic printing technologies have 100 times less electron mobility, Kovio claimed. The company also claims 100 cm2/Vs electron mobility--about the same a polysilicon--for its thin-film CMOS circuits operating at speeds as high as 1 GHz. First-time, read-only memory can be printed with an RFID tag, enabling the inclusion of item-specific information like serial numbers, Kovio said.

"The silicon platform focuses primarily on item-level intelligence--adding intelligence to everyday kind of things that include identification," said Vik Pavate, vice president of Kovio. "In the future, [Kovio] will have sensors and displays all integrated into one device."

Current RFID tags require an additional chip to store item-specific information, usually in memories that must be programmed by OEMs. Kovio uses read-only memories that could help reduce manufacturing costs. "Because we use printed [read-only] memory, the cost of programming basically disappears," claimed Pavate.

"We can print all the blocks that are required to make an RFID product--which includes the logic, memory, rectifiers and dividers--because the incoming [RF] signal has to be divided down to the clock of the chip," said Pavate. "You have to be able to print the integrated capacitor, and most importantly you have to print memory."

According to analysts, Kovio's silicon ink circuits may have a significant head start over other printable circuit technologies, such as those using organic transistors. But they added that Kovio's approach has limitations.

"Kovio offers a viable alternative to silicon chip RFIDs using a printed solution. It cannot do everything a high-end silicon chip can do, but can be much cheaper because it does not use a silicon chip, which is the most expensive part of an RFID tag today," said Raghu Das, CEO of IDTechEx (Cambridge Mass.).

Kovio announced no customers for its silicon ink RFID tags, but said it is targeting markets like pharmaceuticals, electronic tickets, package delivery tracking, logistics and asset management.

Kovio's circuitry is printed on 100-micron-thick foils, and includes up to 128 bits of ROM. It uses synchronous tags-talk-first protocols, 106-Kbits/s data rates and includes large bonding pads for attaching cheap antennas. The printing process uses no hazardous liquids or gases.